Fully flexible multi-tuner front end architecture for a receiver

ABSTRACT

In an example, a method includes: in a first mode, causing a first tuner of an entertainment system to receive and process a first RF signal from a first antenna configured for a first band to output a first audio signal of a first radio station and causing a second tuner of the entertainment system to receive a second RF signal from a second antenna configured for the first band to determine signal quality metrics for one or more radio stations of the first band; in a second mode, causing the first tuner to output a first signal representation of the first RF signal and causing the second tuner to receive and process the second RF signal to output a second signal representation of the second RF signal; and causing a phase diversity combining circuit to process the first and second signal representations to output an audio signal of the first radio station, without disruption of output from the entertainment system of a broadcast of the first radio station.

BACKGROUND

In certain radio reception environments such as an automotiveenvironment, multiple antennas and tuners may be present to enable avariety of use cases such as phase diversity reception, dual bandreception, audio and data reception, among others. Existingfully-integrated techniques can share one antenna between multiple radiofrequency (RF) and/or intermediate frequency (IF) signal paths only withdegraded performance on one or both of the signal paths. For instance,if a loop-through buffer is used to feed the RF signal to a secondarypath, the secondary path's performance is generally compromised relativeto the primary path due to the loop-through buffer's RF characteristics.This asymmetric performance is undesirable for a number of reasons.

As another example, if one antenna is connected to two RF inputs, andthose inputs are designed to each present twice the desired terminationimpedance for the antenna, an effective RF split is realized, but thetwo paths will be compromised due to sharing power between the inputs.One solution to this problem is inclusion of an external (to one or moreintegrated tuners) active splitter circuit to buffer the antenna signal.However, this circuit increases component counts, raises costs andcomplexity, including routing issues and power consumption.

SUMMARY OF THE INVENTION

In one aspect, an apparatus comprises a first low noise amplifier (LNA)to receive and amplify a first radio frequency (RF) signal of a firstband, received from a first antenna and a first tuner having a firstplurality of mixers including a first mixer to selectively be coupled tothe first LNA to receive and downconvert the first RF signal receivedfrom the first LNA to a first downconverted signal. The first tuner maybe configured to process the first downconverted signal. In addition,the apparatus further comprises a second LNA to receive and amplify asecond RF signal of a second band, received from a second antenna, and asecond tuner having a second plurality of mixers including a secondmixer to selectively be coupled to the second LNA to receive anddownconvert the second RF signal received from the second LNA to asecond downconverted signal and a first mixer to selectively be coupledto the first LNA to receive and downconvert the first RF signal receivedfrom the first antenna to a third downconverted signal. The second tunermay be configured to be controllable to process a selected one of thesecond downconverted signal and the third downconverted signal providedby a selected one of the second mixer and the first mixer of the secondtuner.

In a first mode of operation, the first LNA is coupled to provide thefirst RF signal to the first tuner and to the second tunersimultaneously. The apparatus may further include a third LNA to receiveand amplify a third RF signal of the first band, received from a thirdantenna, where the third LNA is coupled to provide the third RF signalto the second tuner to enable phase diversity reception of the firstband in a second mode.

In an example, the apparatus may further include an audio processor anda phase diversity combining circuit to seamlessly transition from thefirst mode to the second mode without audible impact to an audio signaloutput from the apparatus.

In an example, the first plurality of mixers further includes a secondmixer to selectively be coupled to the second LNA to receive anddownconvert the second RF signal to a fourth downconverted signal. Theapparatus may further include a first loop-through buffer coupled to anoutput of the first LNA to receive the first RF signal and output thefirst RF signal to a second receiver coupled to the apparatus, where theapparatus includes a first receiver. The apparatus may further include asecond loop-through buffer coupled to an output of the second LNA toreceive the second RF signal and output the second RF signal to thesecond receiver. The apparatus may further include a selector coupled toan output of the first loop-through buffer and an output of the secondloop-through buffer and controllable to output a selected one of thefirst and second RF signals to the second receiver.

In an example, the first tuner may include a multiplexer coupled to anoutput of the first plurality of mixers, the multiplexer controllable toprovide an output of one of the first plurality of mixers to a signalprocessing path of the first tuner. The first tuner may further includea first frequency generator to operate at a first frequency and thesecond tuner may further include a second frequency generator to operateat a second frequency substantially different than the first frequencywhen the first tuner and the second tuner are to operate in a firstband. A filter may be coupled to an output of the first LNA to provide anotch response to reduce coupling from the second frequency generator.In an example, the first LNA, the first tuner, the second LNA and thesecond tuner are configured on a first semiconductor die.

In another aspect, a method includes: in a first mode, causing a firsttuner of an entertainment system to receive and process a first RFsignal from a first antenna configured for a first band to output afirst audio signal of a first radio station and causing a second tunerof the entertainment system to receive a second RF signal from a secondantenna configured for the first band to determine signal qualitymetrics for one or more radio stations of the first band; in a secondmode, causing the first tuner to output a first signal representation ofthe first RF signal and causing the second tuner to receive and processthe second RF signal from the second antenna to output a second signalrepresentation of the second RF signal; and causing a phase diversitycombining circuit to process the first and second signal representationsto output an audio signal of the first radio station, without disruptionof output from the entertainment system of a broadcast of the firstradio station.

In an example, the method further includes, in a third mode, causing thefirst tuner to receive and process the first RF signal from the firstantenna to generate a first audio signal of the first radio signal, andcausing the second tuner to receive and process the second RF signalfrom the second antenna to generate a second audio signal of a secondradio station, and causing a linker circuit to transition from the firstaudio signal to the second audio signal, where the linker circuit is tooutput a final audio signal without impairments due to the transition.

In another example, a non-transitory computer readable medium include(s)instructions that when executed enable the entertainment system toperform one or more methods as described herein.

In yet another aspect, a system includes, at least, multiple antennasand a first integrated circuit (IC) including a first tuner and a secondtuner. In an example, the first IC includes: a first pad to receive afirst RF signal from a first FM antenna and symmetrically output thefirst RF signal to the first tuner and the second tuner, and to a firstloop-through buffer to provide the first RF signal to a second IC; and asecond pad to receive a second RF signal from a second FM antenna andsymmetrically output the second RF signal to the first tuner and thesecond tuner, and to a second loop-through buffer to provide the secondRF signal to the second IC. In turn, the first tuner may have a firstplurality of mixers including a first mixer to receive and downconvertthe first RF signal to a first downconverted signal, a second mixer toreceive and downconvert the second RF signal to a second downconvertedsignal, and a first signal processing path to process a selected one ofthe first downconverted signal and the second downconverted signal. Inturn, the second tuner may have a second plurality of mixers including asecond mixer to receive and downconvert the second RF signal to a fourthdownconverted signal, a first mixer to receive and downconvert the firstRF signal to a third downconverted signal, and a second signalprocessing path dynamically controllable to process a selected one ofthe third downconverted signal and the fourth downconverted signal. Inan example, the first IC may further include a microcontroller todynamically control transitions of the first tuner and the second tunerbetween a plurality of operating modes while a first audio signal isoutput by at least one of the first and second tuners.

In yet another aspect, an IC includes a first voltage controlledoscillator (VCO) to oscillate at a first oscillation frequency, a secondVCO to oscillate at a second oscillation frequency, a first dividercoupled to the first VCO to produce a first LO signal, and a seconddivider coupled to the second VCO to produce a second LO signal. In anexample, the first LO signal and the second LO signal are substantiallyat a common frequency, and a frequency range of the first oscillationfrequency and a frequency range of the second oscillation frequency aremutually exclusive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are block diagrams of a receiver in accordance with anembodiment.

FIG. 2 is a block diagram of a multi-chip radio system in accordancewith an embodiment.

FIG. 3 is a flow diagram of a method in accordance with an embodiment.

DETAILED DESCRIPTION

In various embodiments, a radio receiver including one or more tunersmay have an integrated active splitter to route an incoming RF signal tomultiple paths in a symmetric and seamless manner. Still further,embodiments enable full flexibility in choosing which of multipleantennas feeds which of multiple signal paths. This selection can bechanged dynamically in real time as a radio reception environment and/orlistener station selection changes. An architecture as described hereinallows for fully flexible reception of one or more radio stations forprimary reception, phase diversity reception, secondary reception (e.g.,rear-seat entertainment), background/alternate station scanning, and/ortraffic data reception from one or more antennas with symmetricperformance and/or minimal performance loss.

As will be described further herein, different and dynamic modes ofoperation are possible. For example, reception could begin by receivingan FM station from one antenna connected to a first IF path of a firsttuner. Subsequently, a second antenna may be connected to a second IFpath of a second tuner and tuned to the same station, to realize phasediversity reception. The system could subsequently return to singleantenna reception, and the second IF signal path could be used forbackground station scanning from either antenna input, all withoutperturbing the audio content being listened to from the first IF path.In other use cases, the second path could subsequently be tuned to adigital audio broadcast (DAB) station using a Band-III antenna input forthe purposes of DAB/FM seamless linking. Once the link to DAB audiocontent is made, the first IF path of the first tuner could beconfigured to receive its input from the second Band-III antenna torealize phase diversity reception for DAB. Or the first tuner may beconfigured to perform background scanning, either for DAB or FM bands,while the second tuner is to output the audio content via the second IFpath. In addition to background scanning, the tuners may be used also toobtain supplemental content such as radio broadcast data system/radiodata system (RBDS/RDS) content, traffic message channel (TMC) content,and Transport Protocol Exports Group (TPEG) content. Note that duringany or all of the above modes, selected RF inputs received on-chip viaone or more RF input pads may be output to a downstream component via aloop-through path.

Referring now to FIGS. 1A and 1B, shown are block diagrams of a receiverin accordance with an embodiment. More specifically, receiver 100 may bea multi-tuner arrangement, which may be configured on a singlesemiconductor die. As described herein, receiver 100 provides forintegrated active splitting of incoming RF signals from one or moreantennas, to enable dual tuners to process the same RF signal withsymmetric performance. That is, the same RF signal is providedsimultaneously to the two tuners at the same power level such that thetwo tuners process an identical (or at least nearly or substantiallyidentical) signal. Still further, with active splitting as describedherein, embodiments enable seamless transitions between different modesof operation in which RF inputs from different antennas can beswitchably coupled to the different tuners.

As illustrated in FIG. 1A, receiver 100 includes a number of inputs pads105 ₁-105 ₅. In the illustration shown, each input pad 105 may receivean RF input obtained from a given antenna (not shown in FIG. 1A, as suchantennas may be implemented off-chip). In the embodiment of FIG. 1A,these RF inputs may be received in multiple bands. Specifically, two FMRF inputs (FMA and FMB), two Band-III RF inputs (B3A and B3B), and asingle AM band RF input (AMI) are provided. As illustrated, the incomingRF input signals are coupled to corresponding amplifiers 110 a, 110 b,112 a, 112 b, and 114. In an embodiment, each amplifier may beimplemented as a low noise amplifier (LNA), possibly followed by an RFbuffer.

In some cases, a simple buffer either integrated within the LNAs (asschematically shown in FIG. 1A) or coupled to an output of such LNAs,may be provided to buffer the amplified RF signal. This buffer may beprovided, given that the amplifier output may couple to multiple tuners(and also potentially be output off-chip via a loop-through buffer).Thus to better accommodate this loading, such buffer may be incorporatedwithin the corresponding LNAs or coupled to an output thereof.

In addition, embodiments may further provide a filtering function withinor closely coupled to the output of the LNAs. More specifically, such afilter, which can be a low pass filter having a predetermined notchcapability, can be used to filter noise from a frequency synthesizer ofanother tuner on-die. In one embodiment, this filter may be configuredto have a notch at a frequency substantially around 2.8 Gigahertz (GHz).By providing this filtering capability substantially at the output ofthe LNAs, individual filters at an input of each of downstream mixerscan be avoided.

As discussed above, receiver 100 is a dual-tuner receiver including afirst tuner 130 ₁ and a second tuner 130 ₂. The tuners may be configuredas intermediate frequency (IF) tuners to downconvert and process theincoming signals at a given IF frequency. However embodiments are not solimited and in other cases, the tuners may be configured as low IF orzero-IF (ZIF) tuners. With reference first to first tuner 130 ₁, a setof mixers 120 ₁₁-120 ₁₅ are provided. As seen, each mixer is coupled toreceive an incoming amplified RF signal from one of amplifiers 110 a/b,112 a/b, and 114. In turn, each mixer 120 downconverts the received RFsignal with a mixing signal, received from a local oscillator (LO) 124₁, which in turn receives an incoming clock signal, generated by an RFsynthesizer 122 ₁. In one embodiment, RF synthesizer 122 ₁ may beconfigured for operation at substantially around 3.0 GHz. Depending uponthe frequency of a desired channel or station, LO 124 ₁ may becontrolled (e.g., by an on-chip microcontroller (MCU) 150) to output themixing signal at a given frequency. Further, to enable operation withminimal power consumption, MCU 150 may control the corresponding mixers120 of the different tuners such that only a single mixer of each tuneris active at a given time. Such control may be effected, e.g., bydisabling the non-selected mixers. In some cases, MCU 150 may disablethe LO input to unselected (i.e., unused) mixers 120.

The downconverted signals output by mixers 120 are coupled through aselector 125 ₁ (which in an embodiment may be implemented as amultiplexer) to a programmable gain amplifier 126 ₁. After amplificationand filtering in PGA 126 ₁, the signal is digitized in ananalog-to-digital converter (ADC) 128 ₁. From there the digitizeddownconverted signal may be provided to a signal processing path oftuner 130 ₁, which may perform various additional processing, includingfiltering, gain control, decoding and/or demodulation to output ademodulated signal such as demodulated FM or AM signals. In some cases,depending upon the band of operation, the output of a given tuner 130 ₁may be a modulated signal, such as in the case of DAB or HD input.

As further shown in FIG. 1A, loop-through paths are provided to enableoutput of the amplified RF signals (from the output of amplifiers110/112/114) to be communicated to one or more other components, such asother ICs including tuners or other processing circuits, such asbackground scan or traffic data receivers. Specifically, loop-throughbuffers (LTB) 111 a and 111 b couple to outputs of amplifiers 110 a and110 b, to output a corresponding RF FM signal via loop-through pads (LTAand LTB). As seen, switches S1 and S2 may be controlled (e.g., undercontrol of MCU 150) to enable output of such FM signals. Similarly,loop-through buffers 113 a and 113 b couple to outputs of amplifiers 112a and 112 b, to output a corresponding RF Band-III signal via theloop-through pads, as controlled by switches S1 and S2. As also shown, aloop-through buffer 115 may output an AM RF signal output by LNA 114 viaanother loop-through pad, AMO.

With reference now to second tuner 130 ₂ on the same IC, a second set ofmixers 120 ₂₁-120 ₂₅ are provided. As seen, each mixer is coupled toreceive an incoming amplified RF signal from one of amplifiers 110 a/b,112 a/b, and 114. In turn, each mixer 120 downconverts the received RFsignal with a mixing signal, received from a LO 124 ₂, which in turnreceives an incoming clock signal, generated by an RF synthesizer 122 ₂.In one embodiment, RF synthesizer 122 ₁ may be configured for operationat substantially around 4.4 GHz or another frequency substantiallyseparated from the output of RF synthesizer 122 ₁.

The downconverted signals output by mixers 120 are coupled through aselector 125 ₂ (which in an embodiment may be implemented as amultiplexer) to a programmable gain amplifier 126 ₂. After amplificationin PGA 126 ₂, the signal is digitized in an ADC 128 ₂. From there thedigitized downconverted signal may be provided to a signal processingpath of tuner 130 ₂, which may perform various processing, includingfiltering, gain control, decoding and/or demodulation to output ademodulated signal such as demodulated FM or AM signals, or a modulatedsignal, such as in the case of DAB or HD input.

More specifically, FIG. 1B illustrates high level circuitry furtherpresent in a multi-tuner IC. More specifically, after digitization incorresponding ADCs 128 ₁, 128 ₂ the digitized downconverted signals areprovided to separate signal processing paths of tuners 130 ₁, 130 ₂. Inthe embodiment shown, such tuner circuitry may be implemented as radiodigital signal processors (DSPs) 135 ₁, 135 ₂. As described above,depending upon particular mode and band of operation, radio DSPs 135 mayfurther condition and process the digitized signals and demodulate thesignals to result in demodulated signals, e.g., of an FM band, which canbe directly output from radio DSPs 135.

Still further, additional processing circuitry may be provided. Asshown, an audio processor 140 may be provided to further process thedemodulated signals. In the illustrated embodiment, audio processor 140includes a phase diversity circuit 142. In various embodiments, phasediversity circuit 142 may be configured to receive common content, e.g.,of a given radio station by way of the multiple signal processing pathsand perform phase diversity by selecting a given one of the two signalsfor output, e.g., based on signal quality metrics. In anotherembodiment, phase diversity circuit 142 may be configured to performphase diversity processing based on a maximal ratio combining technique.

As further illustrated, audio processor 140 may further include a linkercircuit 144. In various embodiments, linker circuit 144 may beconfigured to perform seamless linking, such that the same audio contentas obtained from two different antennas (and potentially two differentbands), can be linked together. For example, linker circuit 144 may beconfigured to enable a smooth transition from audio content obtainedfrom an FM signal output to audio content obtained from a DAB signaloutput when reception conditions for the FM signal fall below athreshold (and vice versa). This linking may be performed seamlessly ortransparently to the user, such that the user does not detect thetransition, nor is the audio output adversely affected. As furtherillustrated, audio processor 140 may further include an audio DSP 146,which may perform further audio processing as desired to output a streamto a digital-to-analog converter (DAC) 150, such that an audio output isprovided.

Still further shown, audio processor 140 may further receive incomingaudio input, e.g., from a similarly configured second IC including oneor more receivers/tuners (and/or from a downstream external linkercircuit/demodulator).

Thus in the embodiment of FIGS. 1A and 1B, each tuner 130 can receiveits input from any one of two FM, two Band-III, and one AM RF antennainput. Each RF input can simultaneously drive either or both of the IFsignal paths of these tuners and/or a loop-through buffer for connectingto a downstream receiver such as a background scan or traffic datareceiver. When one RF input is used to feed both IF signal paths, bothpaths will have symmetric performance (which is a desirablecharacteristic in that signal levels, phases, and other characteristicsare identical (or nearly identical)). Another benefit of an architectureas in FIGS. 1A and 1B is that a substantially seamless transitionbetween different operating states can be accomplished entirely on-chipunder control of MCU 150. That is, a transition of operating mode canoccur in a manner transparent to a listener, as the transition occurswithout any audible click, pop, delay or other signal distortion.

In an embodiment, frequency synthesizers 122 ₁,122 ₂ may include LCtank-based voltage controlled oscillators (VCOs) that operate atsubstantially different frequencies, to reduce unwanted coupling. In theexample described above, frequency synthesizer 122 ₁ may operate atapproximately 3.0 GHz, while frequency synthesizer 122 ₂ is to operatesubstantially at approximately 4.4 GHz. Understand that these frequencysynthesizers can be dynamically controlled by MCU 150 to operate at agiven frequency, which may vary depending upon band of operation. In anycase, these frequency synthesizers (and more specifically the VCOsincluded therein) may be constrained from operation within a givenfrequency range of each other. In one embodiment, MCU 150 may controlthe VCOs to maintain a minimum frequency separation of 500 megahertz(MHz). In addition, frequency synthesizers 122 may be controlled to varyfrequency using a rasterization technique, such that any changes to theVCO frequencies occur in steps of at least 500 kilohertz (kHz), tominimize harmful coupling between VCOs and reduce spurs in the LOoutputs.

With this frequency separation of frequency synthesizers 122,frequencies generated by the different VCOs, which may include thefundamental oscillation frequency of each oscillator as well as harmonicfrequencies thereof, avoid coupling to one another, preventing largespurs in each other. By using frequency synthesizers that operate at twovery different frequency ranges (and which are mutually exclusiveranges), the level of the spurs can be greatly reduced, in that the LCtank frequency response of the VCOs can attenuate the energy coupledfrom one VCO to the other. In one example, the LC tanks of the twodifferent frequency synthesizers can be of substantially differentinductances to realize the frequency separation. As one such example, toenable RF synthesizer 122 ₂ to operate at 4.4 GHz, the LC tank may havea given capacitance (e.g., x picoFarads, where x can vary in differentembodiments) and an inductance of approximately 800 picoHenries in anexample embodiment. In turn, RF synthesizer 122 ₁, to operate at 3.0 GHzmay have a capacitance of 1.6 x picoFarads and an inductance ofapproximately 1 nanoHenry.

To further reduce spurs, LOs 124 ₁, 124 ₂ may be implemented withinrespective shielded regions. Two different FM or Band-III stations canbe received within the same IC and not have the spurs that would beassociated when using two VCOs of the same frequency range. Understandwhile shown at this high level in the embodiment of FIGS. 1A and 1B,many variations and alternatives are possible.

Referring now to FIG. 2, shown is a block diagram of a multi-chip radiosystem in accordance with an embodiment. As shown in FIG. 2, system 200may be implemented as an automotive radio system that has multiple tunerchips, namely a first tuner chip 220 and a second tuner chip 260, alongwith a third demodulator chip 250. Understand while shown with threedifferent ICs in this embodiment, in other cases some or all of thehardware circuitry of these three different ICs can be implemented intoone or more die of a single IC. Still further, different variations inthe amount and type of circuitry of each IC is possible.

As illustrated, incoming RF signals are received by a plurality ofantennas 210 ₁-210 ₂. Understand while shown with two antennas for easeof illustration, in many cases a given vehicle may include more than twoantennas. As examples, some vehicles may include two (or more) FMantennas, two (or more) Band-III antennas, and at least one AM antenna.However for ease of illustration, two representative antennas are shown(understanding that this representation of two may actually beimplemented as more than two antennas).

To recover RF signals of given bands, antennas 210 may couple tofilters/antenna switches 215 ₁-215 ₂, which may perform appropriatefiltering to thus output RF signals of at least three bands, namely FM,DAB and AM. In particular vehicle installations, antennas 210 andswitches 215 may be implemented at a given location, e.g., near a rearof a vehicle, as antennas 210 may be implemented on rear windows, rearside windows, a roof or trunk-mounted unit or so forth. Circuitry may beprovided in close proximity to such antennas to provide the RF signals,e.g., via one or more coaxial cables, to tuners 220/260.

In the embodiment shown, tuners 220/260 may be separate instantiationsof the same tuner device. However, these different tuners may bedifferently configured to perform different primary functions. As such,each tuner is shown with different constituent components in FIG. 2.Thus as illustrated, tuner 220 may be configured to operate as a primaryFM and AM tuner, while tuner 260 may be configured to operate as aprimary DAB tuner. More specifically, with reference to tuner 220, itincludes dual tuner circuitry 230 to perform FM phase diversityprocessing, dual FM channel processing (e.g., two different FM channels,one for a primary entertainment system and one for a secondary (e.g.,rear seat) entertainment system), FM and DAB seamless linking, and AMband operations (and of course single channel FM reception).

As such, tuner 220 is configured to directly receive FM RF signals fromantennas 210 ₁ and 210 ₂ via input pads 222 _(a) and 222 _(b). Inaddition, to enable the same signals to be provided to second tuner 260,the incoming FM RF signals may be output via loop-through pads 223 _(a)and 223 _(b). Similarly, as tuner 220 acts as a secondary DAB tuner, itreceives incoming DAB band RF signals indirectly from second tuner 260,rather than directly from antennas 210, via input pads 224 _(a)/224_(b). As further illustrated, tuner 220 receives an AM band RF signalvia input pad 225.

After appropriate processing of one or more FM signals in dual tunercircuitry 230, resulting demodulated signals can be provided to an audiodigital signal processor (DSP) 235 for additional audio processing(e.g., multi-channel processing) such that audio outputs can be providedvia multiple channels 236 _(a)-236 _(c) including correspondingdigital-to-analog converters to enable audio output to desireddestinations (e.g., multiple channels of speakers). As further shown,demodulated FM audio can be output via pad 238 to demodulator 250, asdescribed below. As further shown, blended audio can be received via pad240 to enable further audio processing in audio DSP 235 and output fromtuner 220.

In similar manner, tuner 260 includes dual tuner circuitry 270 toperform DAB phase diversity or multi-ratio combining processing, dualDAB channel processing (e.g., two different DAB channels, one for aprimary entertainment system and one for a secondary (e.g., rear seat)entertainment system), FM and DAB seamless linking.

As such, tuner 260 is configured to directly receive DAB RF signals fromantennas 210 ₁ and 210 ₂ via input pads 264 _(a) and 264 _(b). Inaddition, to enable the same signals to be provided to first tuner 220,the incoming DAB RF signals may be output via loop-through pads 263 _(a)and 263 _(b). Similarly, as tuner 260 acts as a secondary FM tuner, itreceives incoming FM RF signals indirectly from first tuner 220, ratherthan directly from antennas 210, via input pads 262 _(a)/262 _(b). Asfurther illustrated, tuner 260 receives an AM band RF signal vialoop-through pad 265.

After appropriate processing of one or more DAB signals in dual tunercircuitry 270, resulting DAB-modulated signals can be provided todemodulator 250 via pad 266 for demodulation and potentially linkingwith an FM signal from first IC 220.

As further illustrated in FIG. 2, demodulator 250 may be configured todemodulate incoming modulated DAB signals received from tuner 260. Morespecifically, dual tuner circuitry 270 may output DAB signals from bothtuners as two sets of I/Q data to demodulator 250, which may thusdemodulate the DAB signals and provide the demodulated DAB signals tofirst tuner 220 for further audio processing and output. Similarly, whena mode of operation for FM-DAB blending is active, demodulator 250 mayperform seamless linking between the same audio content from these twodifferent bands. To this end, demodulator 250 may include a large amountof memory, e.g., buffer circuitry, to buffer processed audio of aleading one of these bands, so that the common content of the two bandsmay be linked up in time such that transitioning between either streamis not noticeable to the listener. Note also that demodulator 250 mayfurther perform maximal ratio combining (MRC) phase diversity for HDand/or DAB signals.

Understand also that while FIG. 2 shows an implementation with multipleseparate ICs, embodiments are not so limited and in anotherimplementation more than two tuners may be adapted within a single IC,e.g., all adapted on a single semiconductor die or as separate diewithin a multichip module (MCM). In some cases, the externalmodulator/linker 250 also may be implemented within an IC, e.g., on asingle semiconductor die or as part of a MCM.

Referring now to FIG. 3, shown is a flow diagram of a method inaccordance with an embodiment. As shown in FIG. 300, a control logic,such as a hardware-based microcontroller of a tuner, which may be incommunication with a host processor of an entertainment system, may beconfigured to cause a multi-tuner as described herein to perform in awide variety of different operation modes. Understand that the followingdiscussion of FIG. 3 is primarily with regard to receipt and processingof a first radio station desired by a listener. Of course understandthat many of the different modes of operation and transitions betweenthem can occur when a listener desires to tune to a different station.In the various modes of operation described herein, backgroundoperations also may be performed. Such operations, which may beperformed on one or both tuners, can be used to perform background scansof available stations and determine signal quality metrics thereof

In addition, non-audio data such as RDS and/or traffic data may beobtained by these background operations. Information determined by wayof these tuners can be provided to the microcontroller, which in turnmay be in communication, e.g., via a given software applicationprogramming interface (API), with the host processor. As such, the hostprocessor may be the primary initiator of audio system mode transitionsdescribed herein, based on user input and operating program. In turn,the host processor provides instructions to the microcontroller, tocause the microcontroller to flexibly configure and re-configure themulti-tuner to perform in a given mode of operation and transition asappropriate between operating modes.

With reference to FIG. 3, in a first mode of operation (block 310), afirst radio station is tuned using a first FM antenna and a first tuner.After appropriate signal processing of the received FM signal, an audiosignal of the first radio station can be output, from the first tuner toan output of the entertainment system (e.g., speakers).

In another mode of operation (block 320), phase diversity may beperformed to cause this same first radio station to be output by bothtuners as modulated signal to be combined in a phase diversity combiningcircuit, and thereafter demodulated and output as an audio signal. Here,each tuner is coupled to a different antenna, to enable this phasediversity operation. This transition may be initiated when the firstantenna suffers an impairment in signal reception, e.g., due tomultipath fading. Note that the transition between single antennareception and phase diversity reception may occur seamlessly, that iswithout any audio artifact, pop, click or other audible distortion.

At block 330 another mode of operation may occur to perform backgroundscanning. More specifically, the microcontroller may cause the secondtuner to be switched to a background scan mode to determine signalquality metrics for one or more background radio stations (as well asfor the first radio station). As discussed above, this information asdetermined in the second tuner can be provided to the microcontrollerthat in turn provides it to the host processor. In this mode, the firsttuner may continue to tune and output the first radio station.

In addition to determining signal quality metrics for FM channels, thetuner may also perform such background scan operations with regard toDAB channels. As such, in another mode of operation as shown at block340 this second tuner may be switched to receive an input from aBand-III antenna to perform such background scanning. In this modestill, the first tuner may process and output the first radio station.

Assume that as a vehicle travels, its signal quality for this firstradio station received via the FM band begins to degrade. However,assume also presence of an available DAB channel for this same radiostation. In this instance, at block 350 another mode of operationenables the first radio station to be tuned in a DAB channel via thesecond tuner. These two signals of the same content may then beseamlessly linked, accounting for delay differences between the twosignals. In an embodiment, this seamless linking may be performed bydownstream circuitry such as a separate demodulator/linker chip.Thereafter, operation may continue with the first radio station beingreceived and processed using the DAB channel. Thus at this point thefirst tuner is available, and at block 360 another mode of operationenables phase diversity processing for the DAB channel. As such, thefirst tuner may be controlled to receive a Band-III signal from aBand-III antenna and output the DAB channel to perform phase diversityprocessing.

In some instances, audio content of a given radio station may betransmitted on multiple or alternate frequencies, e.g., where each ofmultiple transmit antennas is located in a different geographiclocation. Assume that a vehicle is travelling such that it begins losingthe signal from a first transmit antenna that transmits at a firstfrequency. However, based on background scanning it is determined thatthe same audio content is available on an alternate frequency, e.g., viaa same or different radio station having a transmit antenna thattransmits at a second frequency. Thus as shown at block 370, alternatefrequency switching may be performed such that the second tuner isswitched to tune to the radio station via an alternate frequency (e.g.,using a DAB input). After appropriate blending, audio content of thisalternate frequency station can be output via the second tuner.

As further shown in FIG. 3, at block 380 (shown in a dashed box as beingoptional), one or more of the received RF signals can be provided to oneor more downstream tuners via bypass paths, such as the loop-throughbuffers described above.

Understand while shown with these particular modes of operation andswitching of control between the different tuners is shown, manyvariations and alternatives are possible. Furthermore, while specifictransitions between the different modes of operation are describedabove, it is possible for many other transitions between the modesdescribed above and other modes to occur. Still further, while specificrepresentative tuners to process given RF signals from given antennaswere discussed above, understand that such selection is arbitrary, and agiven programming of an MCU or other control logic with programmableinstructions stored in a non-transitory storage medium may call for theoperation to be performed by different tuners or combinations of tuners.And while the above examples relate to AM, FM and DAB bands, embodimentsapply to tuners and control logic configured for additional radio bands.

While the present invention has been described with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations therefrom. It is intended that the appendedclaims cover all such modifications and variations as fall within thetrue spirit and scope of this present invention.

1. An apparatus comprising: a first low noise amplifier (LNA) to receiveand amplify a first radio frequency (RF) signal of a first band,received from a first antenna; a first tuner having a first plurality ofmixers including a first mixer to selectively be coupled to the firstLNA to receive and downconvert the first RF signal received from thefirst LNA to a first downconverted signal, the first tuner to processthe first downconverted signal; a second LNA to receive and amplify asecond RF signal of a second band, received from a second antenna; and asecond tuner having a second plurality of mixers including a secondmixer to selectively be coupled to the second LNA to receive anddownconvert the second RF signal received from the second LNA to asecond downconverted signal and a first mixer to selectively be coupledto the first LNA to receive and downconvert the first RF signal receivedfrom the first antenna to a third downconverted signal, the second tunercontrollable to process a selected one of the second downconvertedsignal and the third downconverted signal provided by a selected one ofthe second mixer and the first mixer of the second tuner.
 2. Theapparatus of claim 1, wherein in a first mode of operation, the firstLNA is coupled to provide the first RF signal to the first tuner and tothe second tuner simultaneously.
 3. The apparatus of claim 2, furthercomprising a third LNA to receive and amplify a third RF signal of thefirst band, received from a third antenna, the third LNA coupled toprovide the third RF signal to the second tuner to enable phasediversity reception of the first band in a second mode.
 4. The apparatusof claim 3, wherein the apparatus further comprises an audio processorand a phase diversity combining circuit to seamlessly transition fromthe first mode to the second mode without audible impact to an audiosignal output from the apparatus.
 5. The apparatus of claim 1, whereinthe first plurality of mixers further includes a second mixer toselectively be coupled to the second LNA to receive and downconvert thesecond RF signal to a fourth downconverted signal.
 6. The apparatus ofclaim 1, further comprising a first loop-through buffer coupled to anoutput of the first LNA to receive the first RF signal and output thefirst RF signal to a second receiver coupled to the apparatus, theapparatus comprising a first receiver.
 7. The apparatus of claim 6,further comprising a second loop-through buffer coupled to an output ofthe second LNA to receive the second RF signal and output the second RFsignal to the second receiver.
 8. The apparatus of claim 7, furthercomprising a selector coupled to an output of the first loop-throughbuffer and an output of the second loop-through buffer and controllableto output a selected one of the first RF signal and the second RF signalto the second receiver.
 9. The apparatus of claim 1, wherein the firsttuner comprises a multiplexer coupled to an output of the firstplurality of mixers, the multiplexer controllable to provide an outputof one of the first plurality of mixers to a signal processing path ofthe first tuner.
 10. The apparatus of claim 1, wherein the first tunercomprises a first frequency generator to operate at a first frequencyand the second tuner comprises a second frequency generator to operateat a second frequency substantially different than the first frequencywhen the first tuner and the second tuner are to operate in a firstband.
 11. The apparatus of claim 10, further comprising a filter coupledto an output of the first LNA to provide a notch response to reducecoupling from the second frequency generator.
 12. The apparatus of claim10, wherein the first LNA, the first tuner, the second LNA and thesecond tuner are configured on a first semiconductor die.
 13. Anon-transitory computer readable medium including instructions that whenexecuted enable an entertainment system to: in a first mode, cause afirst tuner of the entertainment system to receive and process a firstradio frequency (RF) signal from a first antenna configured for a firstband to output a first audio signal of a first radio station and cause asecond tuner of the entertainment system to receive a second RF signalfrom a second antenna configured for the first band to determine signalquality metrics for one or more radio stations of the first band; in asecond mode, cause the first tuner to output a first signalrepresentation of the first RF signal and cause the second tuner toreceive and process the second RF signal from the second antenna tooutput a second signal representation of the second RF signal; cause aphase diversity combining circuit to process the first and second signalrepresentations to output an audio signal of the first radio station,while a broadcast of the first radio station is output from theentertainment system; and in a third mode, cause the first tuner toreceive and process the first RF signal from the first antenna togenerate a first audio signal of the first radio station, and cause thesecond tuner to receive and process the second RF signal from the secondantenna to generate a second audio signal of a second radio station, andcause a linker circuit to transition from the first audio signal to thesecond audio signal, the linker circuit to output a final audio signalwithout impairments due to the transition.
 14. (canceled)
 15. A systemcomprising: a first integrated circuit (IC) including a first tuner anda second tuner, the first IC including: a first pad to receive a firstradio frequency (RF) signal from a first frequency modulation (FM)antenna and symmetrically output the first RF signal to the first tunerand the second tuner, and to a first loop-through buffer to provide thefirst RF signal to a second IC; a second pad to receive a second RFsignal from a second FM antenna and symmetrically output the second RFsignal to the first tuner and the second tuner, and to a secondloop-through buffer to provide the second RF signal to the second IC;the first tuner having a first plurality of mixers including a firstmixer to receive and downconvert the first RF signal to a firstdownconverted signal, a second mixer to receive and downconvert thesecond RF signal to a second downconverted signal, and a first signalprocessing path to process a selected one of the first downconvertedsignal and the second downconverted signal; the second tuner having asecond plurality of mixers including a second mixer to receive anddownconvert the second RF signal to a fourth downconverted signal, afirst mixer to receive and downconvert the first RF signal to a thirddownconverted signal, and a second signal processing path dynamicallycontrollable to process a selected one of the third downconverted signaland the fourth downconverted signal; and a microcontroller todynamically control transitions of the first tuner and the second tunerbetween a plurality of operating modes while a first audio signal isoutput by at least one of the first and second tuners; and the first andsecond antennas coupled to the first IC.
 16. The system of claim 15,wherein the plurality of operating modes includes a single tunerreception mode, a dual tuner reception mode, a phase diversity receptionmode, and a seamless linking reception mode.
 17. The system of claim 15,wherein in a first operating mode, the first tuner is to output thefirst downconverted signal of a first radio station obtained via thefirst RF signal, the second tuner is to output a second downconvertedsignal of the first radio station obtained via the second RF signalreceived from the second antenna, and a phase diversity circuit is tocombine the first downconverted signal and the second downconvertedsignal to produce an audio output signal
 18. The system of claim 17,wherein in a second operating mode, the first tuner is to output thefirst audio signal of the first radio station obtained via the first RFsignal, and the second tuner is to output one or more signal qualitymetrics of one or more other radio stations.
 19. The system of claim 15,wherein the first tuner comprises a first frequency generator to operateat a first frequency and the second tuner comprises a second frequencygenerator to operate at a second frequency substantially different thanthe first frequency when the first tuner and the second tuner are tooperate at a first band, the first frequency generator coupled to afirst local oscillator coupled to the first plurality of mixers and thesecond frequency generator coupled to a second local oscillator coupledto the second plurality of mixers.
 20. The system of claim 18, whereinthe IC further comprises a first low noise amplifier (LNA) coupled tothe first pad to receive and amplify the first RF signal, the first LNAcomprising a buffer to buffer the amplified first RF signal and outputthe amplified first RF signal to one of the first plurality of mixers,one of the second plurality of mixers, and the first loop-throughbuffer.
 21. An integrated circuit (IC) comprising: a first voltagecontrolled oscillator (VCO) to oscillate at a first oscillationfrequency; a second VCO to oscillate at a second oscillation frequency;a first divider coupled to the first VCO to produce a first LO signal; asecond divider coupled to the second VCO to produce a second LO signal;wherein the first LO signal and the second LO signal are substantiallyat a common frequency, and a frequency range of the first oscillationfrequency and a frequency range of the second oscillation frequency aremutually exclusive.
 22. The IC of claim 21, wherein the IC comprises asingle semiconductor die including a first tuner and a second tuner. 23.The IC of claim 22, wherein the first tuner comprises a first pluralityof mixers each to selectively receive the first LO signal and a secondplurality of mixers each to selectively receive the second LO signal.24. The IC of claim 23, wherein in a first mode the first tuner and thesecond tuner are to process concurrently a common signal band obtainedfrom a first antenna.
 25. The IC of claim 23, wherein in a second modethe first tuner is to process a signal from a first antenna and,concurrently, the second tuner is to process a signal from a secondantenna.